The present invention relates generally to a seal, and more specifically to a seal for sealing an aperture in an object through which one or more elongate article extends and to objects including such a seal.
The present invention finds particular utility as a seal for protecting junctions between elongate articles such as pipes, tubes or cables. The term xe2x80x9ccablexe2x80x9d Will be understood hereinafter to include both conductive cables and bundles of optical fibres. When it is necessary to make connections between elongate articles such as pipes, tubes or cables the junction or splice where such article are joined end-to-end is necessarily less strong and less resistive to environmental agents liable to cause deterioration over time than the article itself.
In the production of, for example, cable systems such as telecommunication or power transmission systems, it is frequently necessary to make splices either to join cables end-to-end or to make a branch. The cables and the splices may be located underground, in conduits or in other environments, inside or outside buildings, but in any event are always at risk to the ingress of environmental agents such as moisture or dust. Underground installations are also subject to pressure, and in particular hydrostatic pressure, whilst above-ground installations suffer from diurnal thermal variations. In order to provide environmental protection for splices in cables or other elongate articles various protective measures are known. Systems utilising an enclosing casing have been found to be particularly valuable. Such casings or enclosed containers have a housing for enclosing the cable connections or splices and at least one aperture in the housing wall through which the cable or cables can extend. To ensure adequate protection a seal should be provided for any such aperture.
There is a need for a seal for sealing an aperture in an object which has a simple construction, is easy to install and provides a good sealing performance.
According to a first aspect of the present invention there is provided a seal for sealing an aperture in an object through which aperture one or more elongate articles extends, which seal comprises:
a first support member having at least one longitudinally extending channel adapted to accommodate and support an elongate article;
a second support member in use longitudinally displaced from the first support member, the second support member having at least one longitudinally extending channel corresponding to that of the first support member; and
a sealing member situated between the first and second support members, the arrangement being such that to accommodate an elongate article within the longitudinal extending channel of the first support member so as to extend through the corresponding channel on the second support member it is necessary for the sealing member to be deformed from its rest configuration.
The present invention not only provides a good seal but also performs the function of gripping the elongate article with respect to the aperture. The deformation of the sealing member by the elongate articles causes the sealing member to seal between and around those articles.
The first and second support members are preferably substantially identical to one another. They may be an integral component, in which case they are joined together by a connecting member. Alternatively the first and second support members may be separate components, which may be optionally joined together by a connecting member which may be integral with one of them.
Each or both of the support members preferably takes the form of a substantially cylindrical body having the said at least one longitudinally extending channel in its periphery. It is preferred that each support member be provided with a plurality of longitudinally extending channels. The channels are open to and extend from the outer periphery of the support member and may take any desired shape or form so as to accommodate the elongate article with which the seal is to be used. They may, for example, be substantially U or V shaped channels. For the accommodation of any connecting member the or each support member may be provided with a longitudinally extending hole, preferably central of the support member and parallel to its longitudinal axis.
The or each support member may be formed from any suitable material and may be elastomeric or rigid in nature. The or each support member may, for example, be formed of a metal, such as aluminium or steel, a naturally occurring elastomeric material such as rubber, or a plastics material, e.g. a polyamide, polycarbonate or polyolefin such as polyethylene or polypropylene.
The sealing member preferably takes the form of a substantially cylindrical block of sealant material. The dimensions of the sealant material block, in particular its cross sectional width, should be at least as great as the corresponding dimension of the first and second support member. The outer dimensions of the sealant material block should, in particular, be greater than the inner dimensions of the longitudinally extending channels so that an elongate article lying in those channels needs to deform the sealant material in order for the elongate article not to be laterally deflected but to lie in a straight line.
The sealing member may generally comprise any suitable sealant. A particular preferred sealant material is a gel sealant. The gel sealant may be any suitable gel or geloid sealant such as silicon, urea or urethane gel. It may take the form of a liquid, extended polymer composition gel sealant, with the polymer comprising an elastomer, or a block copolymer have relatively hard blocks and relatively elastomeric blocks. Examples of such copolymers include styrene-diene block copolymers or styrene-ethylene-propylene-styrene block copolymers. The extender liquids employed in the gel preferably comprise oils, such as naturally occurring hydrocarbon oils, synthetic oils or mixtures thereof. Preferred oils are mixtures of non-aromatic paraffins and naphthenic hydrocarbon oils. Such gels are well known in the prior art.
Any connector member when present may take any suitable form. It may, for example, take the form of a rod formed from any of the materials described above in relation to the first and second support members.
To assist in the support of the elongate articles within the longitudinally extending channels of the first and second support members, additional retaining means may be provided. Such means may take the form of tie wraps and/or tapes or strips. Cable gripping strips could, for example, be wound around the elongate articles either individually or in groups. Such a gripping strip, called an axial pull strip, is disclosed in WO96/09670, which document is incorporated herein by reference. Such strips increase the ability of elongate articles, such as cables, to withstand axial forces and where necessary increase the dimensions of the elongate articles to match the sizes of apertures in the casing.
Additional sealant material may be placed around the elongate articles and the central sealant material if required. Such further sealant material could be used in the form of a tape.
The seal of the present invention has a wide application for the sealing of objects having an aperture. It may, for example, be used as a duct seal, a grommet or xe2x80x9cfeed throughxe2x80x9d in a wall, or the bulkhead of a car or other vehicle. More preferably it may be used for the sealing of an aperture in a closed container for containing optical fibre or electrical splices or connections. Such a container may be supplied with seals according to the first aspect of the present invention pre-installed or the seals may be applied separately and installed when used. The seal is particularly suitable for sealing around several small diameter cables in a cable aperture of a cable splice closure.
According to a second aspect of the present invention is provided a closed container for containing one or more cable splices or connections including a seal according to the first aspect of the present invention.
The container of the second invention may be a cable splice closure such as that described in WO97/45904 which document is incorporated herein by reference. Such a container or cable splice closure contains a housing having at least two parts or half-shells which may be joined together or formed as separate components which are brought together to provide an enclosed container. In addition to the seal of the present invention a sealing material which seals the gap between the cable and housing as it passes through the enclosed container may also be provided. Such sealing material is preferably such that it comes under pressure in use, e.g. by closing the separate parts of the housing or by other means, e.g. by the provision of movable parts of the container. The container, and in particular its housing, may be formed from any suitable material such as those described above for the first and second support member.
The terms longitudinal and lateral refer in general to a direction substantially parallel and substantially perpendicular respectively to the direction in which the elongate article extends.
The present invention is advantageous over known sealing devices and is simpler to use, easier to manufacture and install and yet provides excellent mechanical and environmental protection at the same time as providing effective protection against forces, in particular axial (longitudinal) forces. The strain relief provided with the present invention is easier to achieve than prior art conventional methods requiring the individual wrapping of cables with tape, which is more time consuming as the number of individual cables increases. The present invention also ensures that the cables remain separate, i.e. spaced from, each other to allow the sealing pressure of the sealant material to be well transferred between the cables.